News AMD Nixes Support for PCIe 4.0 on Older Socket AM4 Motherboards, Here's Why

jimmysmitty

Champion
Moderator
Not surprising. There is more than just traces to PCIe. Typically new standards can change those traces, how wide or thick they are or the distances they can travel to qualify for their rated speeds.

The only downside is that AMD should have said something much sooner as a lot of people hyped that as a massive feature.

However considering that PCIe 2.0 is still barely saturated for what this would have given people, it would have only given them the x16 slot and MAYBE the M.2 slot as 4.0, its not a major deal as 3.0 still has plenty of headroom for GPUs.
 
Reactions: King_V
current graphics cards are not going to benefit from pcie4 much--if at all. where you get the kick in the pants is with the new NVMe pcie 4.0 drives coming out. so it's still worth it to get a new mobo. glad I waited to build.
 
Jun 3, 2019
4
3
15
0
taking a bit of the shine of AMD's vaunted backward compatibility with Ryzen processors on the AM4 socke

Why do we expect a mb designed for PCIE3 to support PCIE4 ? The processor runs as promised with backward compatibility. The article tries to show AMD in bad lights because it can't allow PCIE3 ports of older generation to run on PCIE4 magically. Yay, as per the writer AMD broke the promise because the PCIE3 ports can't work as 4.
 
Reactions: King_V and Mandark
exactly. i never bought the hype that pcie4 would be available on old motherboards. not possible, and if it is, it's gimped and full of bugs. not stable, not good, not usable. get a new motherboard
 

Math Geek

Champion
Herald
when reading about AM4 supporting the newer gen chips at no point did i even consider that pcie 4 would work on pcie3 slots, nor that usb 2/3 ports would all of a sudden become thunderbolt ports, that the DDR4 slots would support DDR 5, that the SATA 6 ports would all of a sudden become SATA 12 or anything else magically changing to include features that are not the cpu itself.

not really sure why the author believes this was ever a promise AMD made. they promised the new cpu's would work on AM4 boards and for the most part it does. few of the super budget boards from 2 generations ago can't support it due to BIOS limitations, but overall, they have delivered a lot more than Intel ever has for a socket lasting longer than a year.

if you want bleeding edge, be prepared to pay for it like always. ok with last year's fashions? then enjoy the cost savings the older chipsets will bring you. :)
 

PaulAlcorn

Senior Editor
Editor
Feb 24, 2015
710
63
5,060
0
when reading about AM4 supporting the newer gen chips at no point did i even consider that pcie 4 would work on pcie3 slots, nor that usb 2/3 ports would all of a sudden become thunderbolt ports, that the DDR4 slots would support DDR 5, that the SATA 6 ports would all of a sudden become SATA 12 or anything else magically changing to include features that are not the cpu itself.

not really sure why the author believes this was ever a promise AMD made. they promised the new cpu's would work on AM4 boards and for the most part it does. few of the super budget boards from 2 generations ago can't support it due to BIOS limitations, but overall, they have delivered a lot more than Intel ever has for a socket lasting longer than a year.

if you want bleeding edge, be prepared to pay for it like always. ok with last year's fashions? then enjoy the cost savings the older chipsets will bring you. :)

AMD confirmed directly to us that it would support that feature on older boards. That's why the author feels that way :)
 
Reactions: TJ Hooker
Jun 3, 2019
4
3
15
0
PaulAlcorn Well, even then it isn't a part of backward compatibility. They hoped to deliver something extra which eventually didn't workout. But calling this as a failure to deliver backward compatibility is a bit too much from writer. Just MO.
 

Math Geek

Champion
Herald
really? i saw where they said it could work on some boards but did not see where they promised that.

that would of course change things a bit. if they made a promise before testing it fully and now have to take it back, then i can see where the comments are justified. can you link that release so i can work on my appropriate level of disgust :)
 
I personally always saw it as a bonus rather than anything. I don't recall, for example, in the days of Socket 7, any new features that didn't exist on the board being promised.

I can't imagine in general that customers would be disappointed. PCIe 4.0 was certainly never even thought of when people were buying, say, the B350 and B450 boards, etc. just that the socket would still be usable by new processors up to 2020.

Maybe AMD was a little too hyped when they first said it, though. Still, I'd be shocked of people (outside of trolls, anyway) started screaming and bemoaning the inability to get PCIe 4.0 on older boards. I fully agree with the closing paragraph:
Given the circumstances, AMD is making the right choice here. Complicated support matrices, unofficial (and thus un-warrantied) "support," lowered throughput, and possible data loss are all untenable side effects of giving users what they want -- PCIe 4.0 support on motherboards that weren't designed for the task.
 

pug_s

Distinguished
Mar 26, 2003
333
2
18,815
18
Big disappointment about the Ryzen 3000 cpu's. First there won't be 16 core cpu's and now this. Since Ryzen 1000 cpu's are heavily discounted, I might as well buy one of those and an older gen mobo but get faster memory in order to upgrade later.
 

PaulAlcorn

Senior Editor
Editor
Feb 24, 2015
710
63
5,060
0
Reactions: TJ Hooker

jimmysmitty

Champion
Moderator
taking a bit of the shine of AMD's vaunted backward compatibility with Ryzen processors on the AM4 socke

Why do we expect a mb designed for PCIE3 to support PCIE4 ? The processor runs as promised with backward compatibility. The article tries to show AMD in bad lights because it can't allow PCIE3 ports of older generation to run on PCIE4 magically. Yay, as per the writer AMD broke the promise because the PCIE3 ports can't work as 4.
Maybe because of this:

https://www.pcgamesn.com/amd/400-series-pci-4-0-bandwidth-bios-support-ryzen-3000

https://se7en.ws/your-current-amd-ryzen-motherboard-may-deliver-pcie-4-0-support-for-3rd-gen-cpus/?lang=en

Not to put the blame on AMD but its something that was talked about for quite a while. Even Toms had something on it:

https://www.tomshardware.com/news/amd-ryzen-pcie-4.0-motherboard,38401.html

And had this to say:

We spoke with AMD representatives, who confirmed that 300- and 400-series AM4 motherboards can support PCIe 4.0. AMD will not lock the out feature, instead it will be up to motherboard vendors to validate and qualify the faster standard on its motherboards on a case-by-case basis. Motherboard vendors that do support the feature will enable it through BIOS updates, but those updates will come at the discretion of the vendor. As mentioned below, support could be limited to slots based upon board, switch, and mux layouts.
So yea scratch that, AMD did not nix it and said it would be possible but is now cutting that support. I am fine with it, there is no reason to push something that could have performance and stability issues. I think its a good thing and will help push people to move to the newer platform which will be overall better anyways, especially since the PCIe from the chipset will be updated.
 

salgado18

Distinguished
Feb 12, 2007
567
25
19,020
4
Big disappointment about the Ryzen 3000 cpu's. First there won't be 16 core cpu's and now this. Since Ryzen 1000 cpu's are heavily discounted, I might as well buy one of those and an older gen mobo but get faster memory in order to upgrade later.
Where did you see that there won't be 16 core cpus? Until now, only the 12 core has been announced, but 16 was never denied.
And are you disappointed that old motherboards can't run above what they were designed to do? "Oh no, AMD said their 486 could be compatible with PCI Express 7.0, but now they say it can't, so that's a let down" (exaggerated to make the issue stand out)
 
Reactions: ravewulf
I don't see anything in that prior article claiming AMD promised the feature would be available on older motherboards. Even the title of the article itself uses the term "may", and that officially "AMD says you will lose support for PCIe 4.0 on its older platforms." It sounds like AMD's stance all along was that PCIe 4.0 would be a feature of the new boards, and that it was just some motherboard vendors suggesting PCIe 4.0 could work on their older boards. "Our sources tell us that AMD can simply lock out that feature and that the fate of PCIe 4.0 support on 300- and 400-series motherboards haven't been communicated to them yet."

And sure, in the update section, when contacted AMD apparently clarified that they "will not lock the out feature, instead it will be up to motherboard vendors to validate and qualify the faster standard on its motherboards on a case-by-case basis." That certainly doesn't sound like there was any promised support for the feature, just that some boards might potentially be able to support it. Probably very few if any of these boards ended up meeting the standards for official PCIe 4.0 support.

In any case, I don't think many people will even care about this. Especially since, according to that article, it only worked on the first x16 slot, and not even the M.2 slots. That first slot will typically be fitted with a graphics card, and today's cards are not even anywhere close to needing more bandwidth than what PCIe 3.0 x16 can provide. Most of today's cards will offer practically full performance on even a PCIe 2.0 x16 slot, so the benefits of PCIe 4.0 for graphics cards are likely many years off. The only hardware I can immediately think of that people might want PCIe 4.0 for would be for fast NVME SSDs, but the M.2 slots of these older boards were not expected to support 4.0 anyway.

And even on the new X570 boards, I can't say I'm convinced PCIe 4.0 is a killer feature. It may be desirable for those who want to get every last ounce out of their storage performance with the latest high-end SSDs, and maybe for certain other specialized expansion hardware, but probably not all that useful for most people. The real-world performance benefits of current NVMe drives tend to be minimal over even SATA drives that offer a fraction of the maximum transfer speeds. Even if PCIe 4.0 NVMe drives offer double the theoretical performance, I doubt that will translate to any significant performance gains in the vast majority of common storage tasks.

That doesn't bode well for A-series motherboard pricing with the new motherboards.
That is assuming the A520 boards are even designed to support PCIe 4.0. As far as I know, AMD has only specified that X570 will feature full 4.0 support. The A-series boards are the extreme budget models that don't even support overclocking, so it's very possible that they could stick with 3.0. And that's fine, since budget shoppers are probably not going to be too concerned about not getting maximum performance out of high-end storage hardware. Even on B550, I wouldn't be surprised at all if PCIe 4.0 is only supported on the slots connected to the CPU. Perhaps the first x16 slot and the first M.2 slot would be my guess, while any additional slots controlled by the chipset would likely use 3.0. I can't see mid-range boards requiring a large heat sink with an active cooler on the motherboard chipset like we see with X570 boards.
 

TJ Hooker

Glorious
Herald
I don't see anything in that prior article claiming AMD promised the feature would be available on older motherboards.
Prior article:
"We spoke with AMD representatives, who confirmed that 300- and 400-series AM4 motherboards can support PCIe 4.0. AMD will not lock the out feature, instead it will be up to motherboard vendors to validate and qualify the faster standard on its motherboards on a case-by-case basis."

And now:
"Users today may find a PCIe 4.0 option available in their pre-X570 motherboards. However, users should expect this option to be disabled when final retail BIOSes are released to implement full performance and stability for new 3rd Gen Ryzen processors."

I personally think it's a non-issue, but AMD did backpedal here.
 

Math Geek

Champion
Herald
i can see where it looks that way. but i'm not sure the new press release is about them blocking the feature or more of admitting it is not going to work and letting us know that we'll be seeing manufacturer support pulled before any damage is done to older boards.

they did not say they would work on it but that AMD would not stand in the way if the various brands wanted to pursue it. like others have said, considering it would not have worked on M.2 slots or anything other than the main PCIE slot, it's not really much of a loss overall. if you want to spend big for the new pcie 4 M.2 drives, then you'll have to spend big on the mobo to support it. bleeding edge is never cheap and won't be this time either.

oh well, i'm not gonna lose any sleep over it personally.
 
Reactions: rajag89

13thmonkey

Titan
Moderator
Nixed seems a bit strong, AMD has done nothing wrong, just pointed out it's not reliable as it depends on the mobo makers decisions probably 2 years ago, they have a choice to make their product look bad with bad signals being passed, or ensuring a consistent outcome, I think the laws of physics are at fault here, <insert Scotty joke here>
 
Last edited:
Reactions: rajag89
Jun 3, 2019
4
3
15
0
@ TJ Hooker My point was precisely about "backward compatibility" which means compatible with older equipment. For sure you can run the new processors over the older equipment which was designed to run PCIE 3.0. So that means what is expected by definition is provided. Every new generation will have certain new features which we can not expect to be added to older generations. That is never a part of backward compatibility. Hence, you shouldn't complain about backward compatibility at all tbh.

Regarding the support of PCIE 3.X or 4.0 support in older generation. How could AMD dare to take risk when we have forums who exaggerate holding off an additional feature as taking shine off backward compatibility. Wouldn't you all write the whole third generation as a flop and a total unplanned mess if Mobo vendor ruin things ?
 
Last edited:

PaulAlcorn

Senior Editor
Editor
Feb 24, 2015
710
63
5,060
0
I don't see anything in that prior article claiming AMD promised the feature would be available on older motherboards. Even the title of the article itself uses the term "may", and that officially "AMD says you will lose support for PCIe 4.0 on its older platforms." It sounds like AMD's stance all along was that PCIe 4.0 would be a feature of the new boards, and that it was just some motherboard vendors suggesting PCIe 4.0 could work on their older boards. "Our sources tell us that AMD can simply lock out that feature and that the fate of PCIe 4.0 support on 300- and 400-series motherboards haven't been communicated to them yet."
1.) AMD said it would not lock out the feature.
2.) AMD has locked out the feature.
 
Reactions: TJ Hooker

jimmysmitty

Champion
Moderator
i can see where it looks that way. but i'm not sure the new press release is about them blocking the feature or more of admitting it is not going to work and letting us know that we'll be seeing manufacturer support pulled before any damage is done to older boards.

they did not say they would work on it but that AMD would not stand in the way if the various brands wanted to pursue it. like others have said, considering it would not have worked on M.2 slots or anything other than the main PCIE slot, it's not really much of a loss overall. if you want to spend big for the new pcie 4 M.2 drives, then you'll have to spend big on the mobo to support it. bleeding edge is never cheap and won't be this time either.

oh well, i'm not gonna lose any sleep over it personally.
They said they would not lock the feature out and that it would be up to motherboard manufactures to verify and add in the support, much like CPUs with BIOS updates. Just because a Ryzen 3000 is supported doesn't mean a motherboard manufacture will release the update to support it.

Now they are locking the feature out, for good reason mind you. However this looks bad even though the majority of people wont care.
 

ASK THE COMMUNITY

TRENDING THREADS